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Full text of "The Cambridge Natural History"

xi                               EOCENE ARTIODACTYLES                           333
Tihese general characters only just serve to differentiate the
family; but they illustrate its archaic character, in which it
resembles the Xiphodontidae, and even more the Anthraco-
theriidae. A survey of some of the genera which have been
assigned to the family will bring out other features in the
organisation of these very ancient Artiodactyles.
^A.noplotherinm is so called on account of the fact that it is,
like all ancient Artiodactyles, without liorns or claws. Tusks it
might have, but as a matter of fact lias not. There are, as in
Artiodactyles generally, nineteen dorso-lumbar vertebrae; the
long tail lias numerous chevrons. The shoulder Made has a well-
marked acroinion and a distinct coracoid process; it is wide
proximally. The bones of the fore-arm and fore-leg are* as is
usual in primitive Artiodactyles, separate.
In the skull the chief features, in addition to that mentioned
in tiie definition of the family, are the large size of the par-
occipitdl processes; there is no fossa luchryinalis or deficiency in
the side of the face. The animal is three-toed, both in the fore-
and hind-limbs. The second toe is nearly as large as the Artio-
dactyle third and fourth. There are tiny rudiments of the two
remaining' fingers. The hind-foot is also three-toed, and there is
a trace of the hallux. The fingers are so widely separated and
divergent from each other that it has been suggested that the
animal had webbed feet and inhabited marshes, in which it swam
by the aid of its long tail. The creature was the size of a Tapir.
Closely resembling ^Anoplotheriufii are a number of other genera.
Diplobune ( = J&yracodontotheriuiri) was much like the last,
but was a more delicately-formed animal. The fingers and toes
(three of each) end in such sharply-pointed phalanges that claws
seem, to be almost suggested. There are several species of this
genus. Dacrytherium differs by the presence of a lachrymal fossa.
DwJio'buTie has four-toed extremities, of which the lateral ones
are more slender and shorter than the two middle ones. As in
other Anoplotheriidae, the anterior premolars are furnished with
a sharp cutting edge.
Order V.
Aquatic Mamnaalia, with but few scattered hairs; hind-limbs
absent; fore-limbs paddle-shaped ; tail flattened* and either Whale-